This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
篸 combines 竹 (bamboo) with 參, which likely contributes sound. The exact historical meaning is uncertain, but it may relate to a bamboo implement or a state of unevenness.
Bamboo 竹 over 參 suggests a bamboo tool or something uneven, but the exact meaning is unclear. Picture a bamboo ruler that is not straight, giving uneven measurements.
For シン, imagine a thin bamboo skewer that is uneven: thin -> シン, and the skewer is made of bamboo but not straight.